Last Friday I was excited to finally get to see a project I’d been hearing a lot about. In my two years working at an architecture firm in Boston, I became involved with Passive House New England, a group of local building professionals interested in high-performance design. The Passive House Standard originated in Germany and is beginning to gain traction over here. It is achieved through measured performance statistics, a unique approach that ensures that certified buildings operate at less than 80% of the energy of a to-code building. Basic principles include super-insulated walls, tight air sealing, triple-glazed windows, heat recovery ventilators, and low-energy heat systems such as heat pumps. It’s a house that could be heated by a hair dryer!
Through PHNE, I met the firm Placetailor, a Roxbury-based firm who are passionate about design-build, urban living, and high-performing houses. All of their team members both design and build their projects, and they’ve also begun working as their own developers. The project I visited last Friday was one where they played all three roles.
It’s an interesting project especially because of its urban environment, which for Passive Houses in the US is still a little unusual. They had to address things like the three-story building ten feet from the south facade, making passive solar gain difficult.
Located in Jackson Square in Roxbury, the Rocksberry House plays on the stylistic language of the surrounding neighborhood, and from the exterior doesn’t appear too different from the adjacent structures. Once inside, however, there are a few markers of the house’s incredible capabilities.
First, there are the huge window wells. The walls are filled with 17.5″ of cellulose insulation, which for this frigid January evening with 100 people occupying the space and just one heat pump turned on, meant that the back door had to be opened to cool down the space.
Then, there’s this heat pump. There are two of these in the house, one upstairs and one downstairs. Despite its cold climate, the house will stay warm enough through most of the year through thick walls, use of appliances, body heat, and some passive solar gain. The heat pumps serve as back-up heat for the coldest weeks of the year, and can also be used for cooling in the summer.
There’s this heat recovery ventilator (HRV) tucked away with the other utilities. Since this is a super tight house, air flow is really important. In old houses, leaks caused by old materials or poor construction can lead to great (uncontrolled) ventilation, but poor heating efficiency. A Passive House shouldn’t have any leaks, so it’s important to control air exchanges. The HRV allows exterior air to flow regularly into the house through an exchanger that mixes the indoor and outdoor air before it enters the house, bringing the exterior air up to the indoor temperature and improving air quality. (This project has not been officially certified as a Passive House, but it has met all the performance requirements.)
The fresh air is then vented to bedrooms and out of kitchens and bathrooms through these:
The other cool thing about Placetailor? The crew. They all like cooking and provided this feast for the 100 people who came:
At the open house, they also premiered this video about their work, if you’re interested in learning more!